Every words stands for unique digit that makes the arithmetic equation true

SEVEN + SEVEN + SIX = TWENTY.

What are the digits ?

What is black when you buy it, red when you use it, and gray when you throw it away?

What four weights can be used to balance from 1 to 30 pounds?

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

Can you name any English verb that becomes its past tense by simply rearranging the alphabets ?

You have 10 balls with you. A friend of yours out of nowhere asks you to place those ten balls in five lines such that each of the lines has exactly 4 balls on them. He needs to check your intelligence. Prove him by doing the task.

James bond was pushed out of an aeroplane without any parachute.
He survived, How come?

Mr. Buttons was all set to go to the village of Buttonland to meet his friend. So, he packed his bags and left for the village at 5 in the morning. Upon travelling on a road for miles, he came across a point where the road diverged into two. He was confused on which road to take. He gazed around and he saw two owls sitting on a branch. He thought he could ask for directions for the village from the two owls. So he went to the tree. There he saw a sign which read, "One owl always lies, and one is always truthful. They both fly away if you ask them more than 1 question."
Mr. Buttons was caught in the dilemma of what to ask? And from which owl to ask, since he only had one question. What should Mr. Buttons ask?

John was piloting a plane behind a car but was never able to overtake it. Why?

Luis Garavito killed Density x Volume.

Who is Luis Garavito ?